In Green Change, you can not convert (exchange) any cryptocurrencies to fiat currencies (USD/EUR).
If you wish to receive fiat, you can transfer your cryptocurrency to Top Change; as shown in the link below.
Note! Green Change does not support Rial.
Note! You can only transfer from Tether (USDT) wallet of GC to fiat wallets of TC. Therefore, if you have any currency other than Tether, you have to convert it to Tether (USDT) first. You can see how to convert other cryptocurrencies to Tether in the link below.